Abstract: A method for the simulation of the acoustical quality produced by a virtual sound source and for the localizing of this source with respect to one or more listeners, and one or more original sound sources. This method consists in: 1) fixing values of perceptual parameters defining the acoustical quality to be simulated and values of parameters defining the localization of a virtual source, 2) converting these values into a pulse response described by its energy distribution as a function of the time and the frequency, 3) carrying out a context compensation so as to take account of an existing room effect, 4) obtaining an artificial reverberation from elementary signals so as to achieve a virtual acoustic environment in real time and control the localizing of the virtual source. This method can be used to modify sound signals coming from a real source, or to create sound effects on recording media.

Abstract: A method and apparatus for mixing audio signals. Each audio signal is digitized and then transformed into a predefined visual image, which is displayed in a three-dimensional space. Selected audio characteristics of the audio signal, such as frequency, amplitude, time and spatial placement, are correlated to selected visual characteristics of the visual image, such as size, location, texture, density and color. Dynamic changes or adjustment to any one of these parameters causes a corresponding change in the correlated parameter.

Abstract: The device simulates actively an acoustical impedance. The simulation is achieved by sensing the air pressure on the surface of the membrane of an electrodynamic transducer and by moving the membrane with a speed and an acceleration which depend upon the pressure according to the desired impedance function. It can be used in loudspeaker systems with closed housings to eliminate standing waves inside housings.

Abstract: An automatic sound suppression system is automatically disengaged whenever noise in an area and generated counter noise deviate in their reverse phase relationship or if the amplitude of the counter noise deviates from that of the noise. The system can also be automatically disengaged whenever divergence prediction means predicts that sounds of the noise and the counter noise diverge or whenever divergence prediction means predict that sounds of the noise and the counter noise are about to diverge. The system can also operate as a vibration reducing apparatus which is also automatically disengaged whenever divergence prediction means predicts that a vibration and a generated countervibration diverge.

Abstract: A noise suppressor in an image forming apparatus suppresses noise from a drive mechanism during operation. An operation start signal of the drive mechanism is detected. A previously stored secondary sound having a reversed waveform to the waveform of the noise is generated at a noise suppressing position based on the drive operation start signal.

Abstract: A behind-the-ear assistive listening receiver having a housing containing an RF receiver. The housing includes a cavity in which two or more crystal carriers are removably insertable. Each of the crystal carriers contains an oscillation crystal tuned to a particular frequency corresponding to an RF frequency desired to be received by the user. A switch is provided for permitting the user to select one of the oscillation crystals to automatically tune for the RF receiver to the desired RF frequency. Each crystal carrier may contain visible indicia indicating the frequency to which it is tuned, and the carriers may be positioned in the housing so that the indicia are generally visible to others when the receiver is worn by the user. The assistive listening receiver may also include a conventional hearing aid microphone for converting ambient sounds into an electrical hearing aid signal. A mixer is provided within the housing for mixing the hearing aid signal with the RF signal to provide a mixed output signal.

Abstract: The disclosed BTSC encoder includes a left high pass filter means for receiving a digital left channel audio signal and for digitally high pass filtering the digital left channel audio signal and thereby generating a digital left filtered signal; a right high pass filter means for receiving a digital right channel audio signal and for digitally high pass filtering the digital right channel audio signal and thereby generating a digital right filtered signal; a matrix means for receiving the digital left and digital right filtered signals, and including means for summing the digital left and digital right filtered signals and thereby generating a digital sum signal, and including means for subtracting one of the digital left and digital right filtered signals from the other of the digital left and digital right filtered signals and thereby generating a digital difference signal; a difference channel processing means for digitally processing the digital difference signal; and a sum channel processing means for d

Abstract: The present invention resides in an audio amplifier circuit which includes an output terminal of an IC connected to a power amplifier circuit, a resistor having one end connected to a negative feedback input of the power amplifier circuit and the other end connected to a certain terminal other than the output terminal of the IC, a first capacitor connected between the output terminal and a loud speaker and a second capacitor connected between a wiring connecting the output terminal to the loud speaker and the certain terminal. A reduction of low frequency gain determined by a time constant of the first capacitor and an impedance of the loud speaker is corrected by an increase of of low frequency amplification gain determined by a time constant of the second capacitor and the resistor.

Abstract: A static disposition geometry of the transducer systems of stereo headphones starting from the convention disposition of the headphones at the entrance to the ears, diagonally spaced downward in a forward direction (in in the direction of sight of the user). The conventional stereo headphones having essentially hemispherical housings with the transducer systems disposed in the center of the circular support structure closing the hempspherical housings from the users ears are modified by disposing these transducer systems at a position which is defined by a vector pointing forward in the direction of sight and predominately downward. The transducer systems are fixed in this later position. The amount of downward shift is greater than the amount of forward shift and may be greater than two to one.

Abstract: In the method and apparatus for obtaining acoustic characteristics of sound of a broad frequency range of from, for example, 0 to 20 KHz in a relatively short time with high accuracy even though an inexpensive computer is used; multiple sound ray vectors are defined; a virtual space is defined by a polygonal boundary; the propagation history data of the vector is calculated and stored, the vector being reflected at the boundary; and, based on the data, as for each of the vectors, a transient response thereof at an observation point is added to a time-series numerical array and stored, the response being determined on the basis of the reflected vector and a velocity potential determined at the observation point by a micro-area element of the vector defined on the boundary.

Abstract: A signal input at an input terminal (1) is divided into signals of two systems, and the signal of one system is supplied to a low-pass filter (2) and then fed to a downsampling processor (3). The downsampled signal is superimposed with an impulse response of a characteristic to be realized by an FIR filter (4), and outputted to an oversampling LPF (5), wherein a sampling frequency thereof is matched with a sampling signal of an inputted signal. The other signal of the second system of the two systems is extracted only as a high-band signal by a high-pass filter (6). The high-band signal is added to the output of the LPF (5) by an adder (7), and outputted from an output terminal (8). Thus, an accurate frequency response can be reproduced by use of an FIR filter with a short tap length.

Abstract: A vehicle audio system includes overhead speakers connected to an audio source through a control circuit. The control circuit effects signal delays, crossover filtering, and equalization. The overhead speakers are connected to the control circuit and are positioned such that they provide strong front staging and desired surrounding ambiance responsive to the output signals of the control circuit. According to one aspect of the invention, the speakers are mounted directly to the headliner.

Abstract: An equalizer includes first and second differential amplifiers which have a common output and respective separate current sources, a first negative feed back circuit which feeds back a voltage signal extracted from the common output to the first differential amplifier, a second negative feed back circuit which feeds back the voltage signal to the second differential amplifier, and a filter circuit which is provided at either the first or the second negative feed back circuit and which differentiates frequency characteristics during signal amplification in the first and second differential amplifiers. A frequency characteristic is selected through selection of one of the current values of the respective current sources in response to a sound quality adjusting signal.

Abstract: A monolithic integrable mixer network for a mixer console includes a variable gain preamplifier for each sound channel, a summing amplifier whose summing gain is adjustable differently for each sound channel, and a control unit which divides the channel gain for the respective sound channel between the preamplifier and the summing amplifier according to a ratio dependent on the desired channel gain to optimize the noise performance of the mixer network.

Abstract: A digital audio signal processor for adding harmonic content to an input audio signal through a non-linear transfer function with discontinuities. The discontinuities are generated by bit shifting each input value by an amount dependent on the sign and magnitude of the input value. The amount by which the input value is shifted is roughly inversely related to the magnitude of the logarithm of the input value. The transfer function is fractal and so provides increased harmonic content for all signal amplitudes.

Abstract: An active muffler noise cancellation system having an active controller, a speaker housing with acoustic compliance spaces, a duct extension in communication with said speaker housing and adapted to conform a dipole radiation pattern into a plane wave which can be measured by a microphone.

Abstract: An audio signal transmitting apparatus including, an audio transmission signal generating unit for adding an error correction signal to a digital audio signal and encoding and interleaving the result to generate an audio transmission signal; a continuous signal generating unit which generates a continuous signal by repeating the digital control signal to be used for the reproduction of the digital audio transmission signal a predetermined number of times; a multiplexing unit for multiplexing the audio transmission signal and the continuous signal to generate a multiplexed signal; a modulated signal generating unit for modulating the multiplexed signal by a predetermined digital modulation method to generate a modulated signal within a predetermined frequency band; and an optical signal transmitting unit for converting the modulated signal to an optical transmission signal and transmitting the same.

Abstract: An electroacoustical transducing system for exchanging pressure wave energy with a medium that propagates pressure waves includes an electroacoustical transducer having a vibratile surface. At least one low-loss pressure waveguide has one end adjacent to the vibratile surface and the other end adjacent to the medium. At least one acoustic immittance element is imposed in the length of the waveguide dimensioned and positioned to alter the transfer characteristic of the waveguide between the vibratile surface and the medium at the other end.

Abstract: A portable viewable and audible stethoscope for visually and audibly monitoring the vital life signs (e.g. heart beat, lung respiration, artery pulse, intestinal sounds) of a patient. The stethoscope includes a large diameter sound absorbing cup and a small diameter sound absorbing connected to opposite ends of a tubular connector and an output device enclosed within a hand held case that is connected to a middle region of the tubular connector by a supporting tube. The tubular connector is provided with an internally installed microphone which converts the absorbed sounds to electrical signals. The output device includes an electronic circuit assembly for amplifying the signals from the microphone, an oscilloscope for displaying the signals, and a speaker for converting the signals into audible sounds. The outside of the case of the output device is provided with control switches for the oscilloscope display, speaker volume adjustment and power on/off.

Abstract: In an audio communication control unit, audio signals from at least three terminals connected to a switching part are branched to left- and right-channels audio signals, then the left- and right-channel audio signals are processed using sound image control parameters in such a manner as to impart them with target positions different for each terminal, then all left-channel audio signals corresponding to the respective terminals are mixed together into a left-channel mixed audio signal and all the right-channel audio signals are mixed together into a right-channel mixed audio signal, and these left- and right-channel mixed audio signals are distributed and sent to all the connected terminals.